A team of European researchers claims to have found not only the root cause of gray hair, but also a treatment for the condition. Additionally, their treatment may help people with vitiligo, a condition that causes the loss of pigment in patches of skin, they say.

It's been known for years that hair turns gray due to a natural buildup of hydrogen peroxide in hair follicles, which causes oxidative stress and graying. (Hydrogen peroxide solutions have been used for years as a cheap and easy way to "go blonde.") [8 Tips for Healthy Aging]

In younger people, an enzyme called catalase breaks down hydrogen peroxide into water and oxygen. But lower levels of this enzyme, combined with lower levels of enzymes called MSR A and B that repair hydrogen peroxide damage, cause hair to turn gray as people age.